can i lock my zoom in position while sculpting?
You can temporarily disable Zoom event in the User Preferences.

Zoom in/out to position you'd like so to work comfortable. Then open the window with Ctrl Alt U, type Zoom in the search input textbox and look for the event in the 3D View, to disable/enable simply check/uncheck that option (exact option depends on the type of zooming that you use so frequently):



You may want to leave the User Preferences window opened while you work so not to search for options you've changed.

Note that still you will be able to zoom with other ways in the 3D View window, and using any way in other windows.